for those who prefer hellsatan's way of using phpinclude, follow all the same steps listed above EXCEPT Step 3.
The alternative to step 3 is putting the following code in your phpinclude template, at the very bottom:
PHP Code:
if ($bbuserinfo['userid']<1)
{
eval("\$unreg_navbar = \"".gettemplate("unreg_navbar")."\";");
}
else {
eval("\$loggedin_navbar = \"".gettemplate("loggedin_navbar")."\";");
}